iMac or Mac Mini?

Hello everybody,

I need help with choosing an iMac or Mac mini. Obviously it would be cheaper to go with the mac mini, but money isn't an issue here. I do need a decent graphic card, but on my macbook pro the intel hd graphics 4000 is pretty good. If I were to get a mac mini I'd be using a 23" dell monitor, if I go with the imac i'd be using the 21.5". What benefits would the iMac give me over the mac mini, or the mac mini over the iMac in terms of how long it would last, how fast it is, and the general things.

Thanks,,,,